Conventionally, there is a known substrate transfer apparatus that includes: a hand configured to grip the edge portion of a semiconductor substrate, from which a semiconductor device substrate is produced; and a manipulator to which the hand is attached. For example, Patent Literature 1 proposes a substrate transfer apparatus of such kind, which is configured to transfer a substrate in a vertical orientation. The “vertical orientation” herein means the orientation in which the main surface of the substrate faces substantially in the horizontal direction (i.e., the main surface of the substrate extends vertically).
The substrate transfer apparatus described in Patent Literature 1 includes a chuck hand capable of: retrieving and feeding a substrate in a vertical orientation; and retrieving and feeding a substrate in a horizontal orientation. The chuck hand includes: a flat plate member; at least one fixed engagement member engageable with the edge of a substrate; at least one movable engagement member; and at least one auxiliary engagement member. The movable engagement member and the auxiliary engagement member are movable toward the center of the substrate in a reciprocating manner, and are operated by separate drive units, respectively. The auxiliary engagement member engages with the substrate at a position close to an engagement position where the movable engagement member engages with the substrate.
In a case where the chuck hand thus configured retrieves a substrate in a vertical orientation from a groove in which the substrate is placed, first, the orientation of the chuck hand is controlled such that the movable engagement member is positioned below the substrate, and also, the chuck hand is moved to a position corresponding to the substrate. At the time, it is not always the case that a groove of the movable engagement member is facing the edge portion of the substrate with no positional error. Therefore, first, the fixed engagement member and the substrate are brought into engagement with each other. While keeping this engagement state, the auxiliary engagement member is moved forward and brought into engagement with the substrate, and thereby supplementary gripping of the substrate is achieved by the auxiliary engagement member and the fixed engagement member. Thereafter, the movable engagement member is moved forward, and thereby the substrate is gripped by the movable engagement member and the fixed engagement member. Thus, even if there is a positional error between the groove in which the substrate is placed and the groove of the movable engagement member, since the auxiliary engagement member is present between these grooves, the substrate can be fed and received between these grooves without causing local strain in the substrate.